The present invention relates to an optical disc recording and reproducing apparatus and, more particularly to an optical disc recording and reproducing apparatus which uses an optical disc of a large capacity which requires high precision in control of recording and reproduction, as a recording medium.
The optical disc is a general term of disc-shaped recording media such as a compact disc, a video disc, a phase-change optical disc, a DVD (digital video disc) and the like, which reflect laser beams on recording surfaces thereof, and read recorded signals by the use of reflected beams.
There are read-only and recordable optical discs. The recordable optical disc includes a WORM (Write Once, Read Many) disc and a rewritable disc. CD-ROMs (Compact Disc Read-Only Memories) are typical of the read-only disc. Manufacturers record data such as video, audio, or characters, computer programs, and the like in the CD-ROMs as signals, and distributes them for sale. Users utilize them by reproducing their recorded contents therefrom. Since the WORM disc with a WORM capability and without capabilities of erasing and altering written data, and the rewritable disc with capabilities of erasing and altering written data, can be used to record data therein and can be accessed randomly by users, and are relatively high-speed and large-capacity recording media, they are suitable for use in recording video data or audio data, or suitable for a storage in a computer system.
In the optical disc, as in the case of a magnetic disc recording medium such as a floppy disc or a hard disc, the recording surface on the disc has concentric circular tracks and linear areas in the radial direction thereof, i.e., sectors, which are managed as unit areas, and address information relating to addresses is recorded in specific recording positions indicated by the addresses.
An optical disc recording and reproducing apparatus according to the prior art which records data in the optical disc and reproduces data therefrom, uses an optical head which converges the laser beams to the recording surface thereby reading a signal recorded therein. To read recorded contents including address information, it is required that the optical head be moved to an appropriate position on the recording surface with high precision. For this purpose, feed back control is performed, including tracking control for positioning the head in a desired position of the disc or control of disc rotation for recording/reproduction, as in the case of the magnetic disc medium.
In addition to these control, the apparatus which uses the optical disc requires focusing control for appropriately converging the laser beams to the recording surface, and laser power control for adjusting intensity of the laser beams. Hence, the optical disc reproducing and recording apparatus according to the prior art obtains a tracking error signal or a focus error signal from the reflected beam, and based on these signals, a servo system performs feedback control of the position of the optical head or the laser power. Likewise, the servo system performs the feedback control to rotation of the disc by the servo system.
The optical disc is basically used to record a digital signal therein as a recording medium. The signal recorded in the optical disc is reproduced by irradiating xe2x80x9cpitsxe2x80x9d formed on the optical disc with a laser beam and reading variations in the intensity of the reflected beam or microscopic signals. In this case, because of optical or electrical low-pass frequency characteristics in a reproducing system, even though data has been digitally recorded in the optical disc, reproduced waveform thereof becomes analog signals having intermediate values.
Accordingly, the optical disc recording and reproducing apparatus according to the prior art which perform the control described above, subjects the signal read from the optical disc to binarization, and performs various types of control processes by using the analog processing system and the digital processing system which handles the binarized digital signal and performs highly precise and high-speed processing.
With recent remarkable development of multi media or computers, optical disc recording media of higher density and larger capacities have been developed. The higher density recording requires more highly precise control, while a demand for higher-speed processing goes on increasing. Accordingly, there is a need for an optical disc recording and reproducing apparatus which can handle a large-capacity optical disc recording medium that is capable of executing more highly precise control and performing higher-speed processing including control than the prior art apparatus.
As the large-capacity optical disc, there has emerged an optical disc which employs a recording method different from that of a conventional optical disc recording medium. While the conventional optical disc medium generally has grooves along tracks, and contains signals recorded in either of convex and concave portions thereof, some optical discs contain signals recorded in both portions. This type of optical disc generally has address areas in which respective address information is recorded for recording in the convex and concave portions, and further, the address areas have been utilized as those having both areas of convex and concave portions, to increase recording capacities. In this optical disc, the address area has no grooves described above, and therefore, the address area and the other recording area must be controlled in different manners.
However, the optical disc recording and reproducing apparatus according to the prior art, is not capable of performing high-speed and highly precise control for the large-capacity recording medium, and has difficulty in appropriately changing control of the optical disc which has the address area and the other area, the structures of which differ from each other.
It is an object of the present invention to provide an optical disc recording and reproducing apparatus which is capable of executing highly precise control, thereby recording and reproducing data speedily, by the use of a high-density and large-capacity optical disc as a recording medium.
It is another object of the present invention to provide an optical disc recording and reproducing method which is capable of executing highly precise control, thereby recording and reproducing data speedily, when recording a signal and reproducing a recorded signal by the use of the high-density and large-capacity optical disc as the recording medium.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific-embodiments described are provided only for illustration since various additions and modifications within the spirit and scope of the invention will be apparent to those skill in the art from the detailed description.
According to a first aspect of the present invention, an optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises: analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; address detecting means for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the synchronous clock signal and the signal output from the address detecting means; and gate signal generation switching means for generating a gate signal which controls the analog processing means, based on one of the sector count value held in the sector counter and information obtained from the analog processing means, according to the signal indicating that the address has been detected, which is output from the address detecting means. Thereby, according to the detection of the address, switching is performed so that the gate signal for controlling the analog processing system is based on the sector counter value or based on the information obtained from the analog processing system.
According to a second aspect of the present invention, in the optical disc recording and reproducing apparatus of the first aspect, the information from the analog processing means which is obtained by the gate signal generation switching means is an envelope signal indicating existence of a signal on the optical disc, which is generated by the binarization unit. Thereby, according to the detection of the address, switching is performed so that the gate signal for controlling the analog processing system is based on the sector counter value or based on the envelope signal.
According to a third aspect of the present invention, an optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; and clock selecting means for selecting one of the synchronous clock signal and a clock signal based on the information obtained from the analog processing means, and outputting the selected clock signal as a selection clock signal used for controlling the analog processing means. Thereby, depending upon the generation of the clock signal, switching of the clock signal for use in control is performed between the synchronous clock signal and the signal based on the information obtained from the analog processing system.
According to a fourth aspect of the present invention, in the optical disc recording and reproducing apparatus of the third aspect, the information from the analog processing means which is obtained by the clock selecting means is a rotation clock signal based on the rotation of the optical disc, which is generated by the servo unit. Thereby, depending upon the generation of the clock signal, switching of the clock signal for use in control is performed between the synchronous clock signal and the rotation clock signal.
According to a fifth aspect of the present invention, the optical disc recording and reproducing apparatus of the third aspect further comprises: a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the selection clock signal and a signal output from address detecting means; and gate signal generation switching means for generating a gate signal which controls the analog processing means based on the sector count value held in the sector counter, according to a signal indicating that an address has been detected, which is output from the address detecting means, wherein the gate signal generation switching means, when the clock selecting means has performed switching between the clock signals, does not generate the gate signal based on the sector count value until it receives the signal indicating that the address has been detected, as an input. Thereby, immediately after switching of selection of the clock signal has been performed, the gate signal for controlling the analog processing system generated based on the sector counter value is not used.
According to a sixth aspect of the present invention, an optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; address detecting means for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the synchronous clock signal and the signal output from the address detecting means; gate signal generation switching means for generating a gate signal which controls the analog processing means, based on the sector count value held in the sector counter according to the signal indicating that the address has been detected, which is output from the address detecting means; and flag generating means for supervising generation of the gate signal by the gate signal generation switching means, and updating of the sector count value by the sector counter, generating a flag indicating reliability of the output position of the gate signal, and outputting the flag to the analog processing means. Thereby, when the gate signal for controlling the analog processing system is generated, relationship between the gate signal and updated sector counter value is checked, and the information about of reliability of the output position of the gate signal is transmitted to the analog processing system.
According to a seventh aspect of the present invention, in the optical disc recording and reproducing apparatus of the sixth aspect, the analog processing means decides whether or not to perform processing in accordance with the gate signal, from the flag. Thereby, the processing is performed depending upon the reliability of the output position of the transmitted gate signal.
According to an eighth aspect of the present invention, an optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means for subjecting the signal read from the optical disc to binarization and controlling recording and reproducing a signal in and from the optical disc in analog processing; and gate signal generation switching means for generating a gate signal which instructs the analog processing means to perform switching of gain to be used therein, depending upon a reading result of a signal from the optical disc. Thereby, depending upon the reading result, switching of gain for feedback control is performed.
According to a ninth aspect of the present invention, in the optical disc recording and reproducing apparatus of the eighth aspect, the optical disc has an address area in which address information indicating a physical position on the optical disc is recorded, the address information being recorded in different states in the address area, and the gate signal generation switching means instructs the analog processing means to perform the switching, according to difference between recording states of the address information. Thereby, depending upon the recording states of the address information, switching of gain for feedback control is performed.
According to a tenth aspect of the present invention, an optical disc recording and reproducing method for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises: an analog processing step including a binarization process for subjecting a signal read from the optical disc to binarization and a servo control process for controlling recording and reproducing a signal in and from the optical disc; a synchronous clock generating step for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; an address detecting step for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter step for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the synchronous clock signal and the signal output in the address detecting step; and a gate signal generation switching step for generating a gate signal which controls the analog processing step, based on one of the sector count value held in the sector counter step and information obtained in the analog processing step, according to the signal indicating that the address has been detected, which is output in the address detecting step. Thereby, according to the detection of the address, switching is performed so that the gate signal for controlling the analog processing system are based on the sector counter value or based on the information obtained from the analog processing system.
According to an eleventh aspect of the present invention, in the optical disc recording and reproducing method of the tenth aspect, the information from the analog processing step obtained in the gate signal generation switching step is an envelope signal indicating existence of a signal on the optical disc, which is generated by the binarization process. Thereby, according to the detection of the address, switching is performed so that the gate signal for controlling the analog processing system is based on the sector counter value or based on the envelope signal.
According to a twelfth aspect of the present invention, an optical disc recording and reproducing method for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises: an analog processing step including a binarization process for subjecting a signal read from the optical disc to binarization and a servo control process for controlling recording and reproducing a signal in and from the optical disc; a synchronous clock generating step for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; and a clock selecting step for selecting one of the synchronous clock signal and a clock signal based on the information obtained in the analog processing step, and outputting the selected clock signal as a selection clock signal used for controlling the analog processing step. Thereby, depending upon the generation of the clock signal, switching of the clock signal for use in control is performed between the synchronous clock signal and the signal based on the information obtained from the analog processing system.
According to a thirteenth aspect of the present invention, in optical disc recording and reproducing method of the twelfth aspect, the information from the analog processing step which is obtained in the clock selecting step is a rotation clock signal based on the rotation of the optical disc which is generated by the servo control process. Thereby, depending upon the generation of the clock signal, switching of the clock signal for use in control is performed between the synchronous clock signal and the rotation clock signal.
According to a fourteenth aspect of the present invention, the optical disc recording and reproducing method of the twelfth aspect further comprises: a sector counter step for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the selection clock signal and a signal output in an address detecting step; and a gate signal generation switching step for generating a gate signal which controls the analog processing step based on the sector count value held in the sector counter step, according to a signal indicating that an address has been detected, which is output in the address detecting step, wherein in the gate signal generation switching step, when the clock selecting step has performed switching between the clock signals, the gate signal is not generated based on the sector count value until the signal indicating that the address has been detected is input. Thereby, immediately after switching of selection of the clock signal has been performed, the gate signal for controlling the analog processing system generated based on the sector counter value is not used.
According to a fifteenth aspect of the present invention, an optical disc recording and reproducing method for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises: an analog processing step including a binarization process for subjecting a signal read from the optical disc to binarization and a servo control process for controlling recording and reproducing a signal in and from the optical disc; a synchronous clock generating step for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; an address detecting step for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter step for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the synchronous clock signal and the signal output in the address detecting step; a gate signal generation switching step for generating a gate signal which control the analog processing step, based on the sector count value held in the sector counter step, according to the signal indicating that the address has been detected, which is output in the address detecting step; and a flag generating step for supervising generation of the gate signal in the gate signal generation switching step, and updating of d sector count value in the sector counter step, generating a flag indicating reliability of the output position of the gate signal, and outputting the flag to the analog processing step. Thereby, when the gate signal for controlling the analog processing system is generated, relationship between the gate signal and the updated sector counter value is checked, and the information about of reliability of the output position of the gate signal is transmitted to the analog processing system.
According to a sixteenth aspect of the present invention, in the optical disc recording and reproducing method of the fifteenth aspect, in the analog processing step, it is decided whether or not to perform processing in accordance with the gate signal, from the flag. Thereby, the processing is performed depending upon the reliability of the output position of the transmitted gate signal.
According to a seventeenth aspect of the present invention, an optical disc recording and reproducing method for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises: an analog processing step for subjecting the signal read from the optical disc to binarization and controlling recording and reproducing a signal in and from the optical disc in analog processing; and a gate signal generation switching step for generating a gate signal which instructs the analog processing step to perform switching of gain to be used therein, depending upon a reading result of a signal from the optical disc. Thereby, depending upon the recording states of the address information, switching of gain for feedback control is performed.
According to an eighteenth aspect of the present invention, in the optical disc recording and reproducing method of the seventeenth aspect, the optical disc has an address area in which address information indicating a physical position on the optical disc is recorded, the address information being recorded in different states in the address area, and the gate signal generation switching step instructs the analog processing step to perform the switching, according to difference between recording states of the address information. Thereby, depending upon the recording states of the address information, switching of gain for feedback control is performed.